Count active touches in MultiTouchMotionAccumulator

Counting active touches will allow us to detect first touch on the
device. This information will be used by mapper to getect start of a new
gesture, when the first touch is detected.

Bug: 301055381
Test: atest MultiTouchMotionAccumulatorTest

Change-Id: I53f65daef3e5aa324f42eec6aa85ed6d5ef01bf5
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 64e8825..db31ded 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -58,6 +58,7 @@
         "InputReader_test.cpp",
         "InstrumentedInputReader.cpp",
         "LatencyTracker_test.cpp",
+        "MultiTouchMotionAccumulator_test.cpp",
         "NotifyArgs_test.cpp",
         "PointerChoreographer_test.cpp",
         "PreferStylusOverTouch_test.cpp",
diff --git a/services/inputflinger/tests/MultiTouchMotionAccumulator_test.cpp b/services/inputflinger/tests/MultiTouchMotionAccumulator_test.cpp
new file mode 100644
index 0000000..9fa6cdd
--- /dev/null
+++ b/services/inputflinger/tests/MultiTouchMotionAccumulator_test.cpp
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MultiTouchMotionAccumulator.h"
+#include "InputMapperTest.h"
+
+namespace android {
+
+class MultiTouchMotionAccumulatorTest : public InputMapperUnitTest {
+protected:
+    static constexpr size_t SLOT_COUNT = 8;
+
+    MultiTouchMotionAccumulator mMotionAccumulator;
+
+    void processMotionEvent(int32_t type, int32_t code, int32_t value) {
+        RawEvent event;
+        event.when = ARBITRARY_TIME;
+        event.readTime = READ_TIME;
+        event.deviceId = EVENTHUB_ID;
+        event.type = type;
+        event.code = code;
+        event.value = value;
+        mMotionAccumulator.process(&event);
+    }
+};
+
+TEST_F(MultiTouchMotionAccumulatorTest, ActiveSlotCountUsingSlotsProtocol) {
+    mMotionAccumulator.configure(*mDeviceContext, SLOT_COUNT, /*usingSlotsProtocol=*/true);
+    // We expect active slot count to match the touches being tracked
+    // first touch
+    processMotionEvent(EV_ABS, ABS_MT_SLOT, 0);
+    processMotionEvent(EV_ABS, ABS_MT_TRACKING_ID, 123);
+    processMotionEvent(EV_SYN, SYN_REPORT, 0);
+    ASSERT_EQ(1u, mMotionAccumulator.getActiveSlotsCount());
+
+    // second touch
+    processMotionEvent(EV_ABS, ABS_MT_SLOT, 1);
+    processMotionEvent(EV_ABS, ABS_MT_TRACKING_ID, 456);
+    processMotionEvent(EV_SYN, SYN_REPORT, 0);
+    ASSERT_EQ(2u, mMotionAccumulator.getActiveSlotsCount());
+
+    // second lifted
+    processMotionEvent(EV_ABS, ABS_MT_TRACKING_ID, -1);
+    processMotionEvent(EV_SYN, SYN_REPORT, 0);
+    ASSERT_EQ(1u, mMotionAccumulator.getActiveSlotsCount());
+
+    // first lifted
+    processMotionEvent(EV_ABS, ABS_MT_SLOT, 0);
+    processMotionEvent(EV_ABS, ABS_MT_TRACKING_ID, -1);
+    processMotionEvent(EV_SYN, SYN_REPORT, 0);
+    ASSERT_EQ(0u, mMotionAccumulator.getActiveSlotsCount());
+}
+
+TEST_F(MultiTouchMotionAccumulatorTest, ActiveSlotCountNotUsingSlotsProtocol) {
+    mMotionAccumulator.configure(*mDeviceContext, SLOT_COUNT, /*usingSlotsProtocol=*/false);
+
+    // first touch
+    processMotionEvent(EV_ABS, ABS_MT_POSITION_X, 0);
+    processMotionEvent(EV_ABS, ABS_MT_POSITION_Y, 0);
+    processMotionEvent(EV_SYN, SYN_MT_REPORT, 0);
+    ASSERT_EQ(1u, mMotionAccumulator.getActiveSlotsCount());
+
+    // second touch
+    processMotionEvent(EV_ABS, ABS_MT_POSITION_X, 50);
+    processMotionEvent(EV_ABS, ABS_MT_POSITION_Y, 50);
+    processMotionEvent(EV_SYN, SYN_MT_REPORT, 0);
+    ASSERT_EQ(2u, mMotionAccumulator.getActiveSlotsCount());
+
+    // reset
+    mMotionAccumulator.finishSync();
+    ASSERT_EQ(0u, mMotionAccumulator.getActiveSlotsCount());
+}
+
+} // namespace android